Does anyone know if you can run a 10spd rear derailleur on the new 11spd shifters?? I like the feel of new shimano 11spd but was thinking of putting a shimano XT rear on my new touring bike.
Nope. Won’t work.
Out of curiosity - why? Shimano didn’t change the distance between the cogs so the 11 speed shifters should pull the same amount of cable for each shift as the 10sp did - or am I seeing this wrong? (asking because I’m in a similar situation)
10 and 11 speed road setups may pull the same amount of cable, but you’re mixing in mtb stuff. 10 speed mtb does pull a different amount than 10 speed road.
And actually, contrary to what I think you were alluding to, 10-speed Shimano XT won’t actually work unless you do something to adjust for difference in cable pull between Shimano 10-speed road and MTB shifters. Shimano 10-speed actuation ratios are different on its road and mountain rear derailleurs. I suppose you could still put a 10-speed 11-34 or maybe even 11-36 MTB cogset on there and try and boost your long-cage road rear derailleur with the b-screw turned around.
My bad…missed the part about MTB.
Thanks for the clarification!
Thank you. I think I am just gonna go with a 105 mid/long cage. Still wish I could get a little bigger cassette but I shall see.
Out of curiosity - why? Shimano didn’t change the distance between the cogs so the 11 speed shifters should pull the same amount of cable for each shift as the 10sp did - or am I seeing this wrong? (asking because I’m in a similar situation)
The cogs are not spaced the same. Not even close.
Plus I’ve heard that the 11spd derailleurs do not move the same amount per cable pull as 8,9 and 10 which were all the same.
Sorry…I read it somewhere on the Internets so of course I thougt it must be true 
You are right - according to velonews, the spacing was changed from 2.35 mm to 2.18 mm…
Do you have a link to the VN article?
C to C I get: 10spd = 3.96mm 11spd = 3.85mm
Your numbers indicate 3.95 and 3.78 since the cogs are 1.6mm in both.
What I’d love to know is how they changed the cable pull and derailleurs for 11spd.
to keep same range of motion at shifter for smaller movement at RD? to make it feel easier at shifter? both/neither?
there is a different cable angle at the der(s) from where cable comes in to where it is secured
I’d just like to know what the precise relationship is, to see if there is a combo or jtek that will make up the difference. I’m all about mixing and matching.
Has anyone tried it yet? I am just curious
Here’s the link to the article…it’s Lennard’s answer to a question a little over 1/3 down the page…
It’s worth noting that SRAM did not change the cable pull ratio from 10 to 11 speed, so their 10 speed RDs work with the 11 speed systems.